Blast furnace bell construction

ABSTRACT

An improved bell for blast furnace including arcuate-shaped wear ring segments formed from a laminate consisting of a thick layer of wear-resistant brittle material and a thin layer of ductile material. The outer surface of the wear ring segments is obliquely disposed and the ductile component is disposed below the brittle component. The wear surface of the bell is formed by a plurality of wear rings mounted on a reusable frame by suitable mounting pins. The bell also has a sealing surface formed by a pair of wear ring segments which are releasably secured at the lower end thereof to engage the sealing surface of the loading hopper. The segments which form the sealing surface are again a laminated construction consisting of alternately disposed layers of a brittle wear-resistant material and a ductile impactabsorbing material.

limited idtates Patent llterngtie Feb. 2%, td 72,

[54] BLAST FURNAQE lilllElLlL 2,596,738 5/1952 Thomas ..266/27 ECUNSTRUCTHQW G l M F l enz [72] Inventor: Philip Courtenay Kempe, Brighton, South ggggf z gffiyzg ggzi 5: a

AMmha q Attorney-Fethcrstonhaugh and Co. [73] Assignee: (Ianrun Limited, Montreal, Quebec,

Canada [57] AIEQIFRACT [22] Filed; May 23, 197 1) An improved bell for blast furnace including arcuate-shaped m wear ring segments formed from a laminate consisting of a [21] Appl. No; 411,235 thick layer of wear-resistant brittle material and a thin layer of ductile material. The outer surface of the wear ring segments [30] Foreign Application Priority Dam is obliquely disposed and the ductile component is disposed below the brittle component. The wear surface of the bell is Apr. 22, Canada t l formed a of e gs m ted on a eusable frame by suitable mounting pins. The bell also has a sealing [52] iLSJCl ...2l1 l/36 surface formed by a pair of wear ring Segments which are i] '1 27d releasably secured at the lower end thereof to engage the seal- 38] lField ol Eearch ..214/36, 57; 260/27 ing Surface of the loa ding hoppen The Segments which form 6] mefiemmes Cited the sealing surface are again a laminated construction consisting of alternately disposed layers of a brittle wear-resistant UNITED STATES PATENTS material and a ductile impact-absorbing material.

2,559,763 7/1951 Ginder et a1 ..266/27 117 Claims, 5 Drawing Figures SHEET 1 OF 3 F I G. 20

INVENTOR. PHI LIP C. KEMPE ATTORNEYS PATENTEUFEBZQ I972 SHEET 2 OF 3 lNVliNl'UR.

PHILIP C. KEMPE ATTORNEYS 3,6d5All PATENTEDFEB 29 1972 SHEET 3 [1F 3 INVEN'I'OR.

PHILIP C. KEMPE fla /,4.

I ATTORNEYS llllLAS'll' FURNACE BELL lZONSTlRUQTllUIN FIELD "OF INVENTION This invention relates to improvements in blast furnaces. In particular, the present invention relates to improvements in the charging bell construction of blast furnaces.

lRlOR ART ldeally, a blast furnace should operate continuously over the full working life of the furnace lining. In practice, the efficiency of a blast furnace is very often reduced considerably due to excessive wear occurring in the raw materials charging system at the furnace top, in particular the bell and hopper assembly. As the raw materials enter the furnace, they pass over the bell rod which supports the bell assembly and the cone shaped surface of the bell and enter the furnace between the sealing surface of the bell and the sealing surface of the hopper.

Numerous attempts have been made to improve the wear resistance of the bell rod, bell, and bell sealing surfaces. in some instances, this has been done by employing a wear-resistant material in the form of liners which are located about the various surfaces which are subjected to wear. Conventional wear-resistance materials which might be economically used for this purpose are generally of a very brittle nature such that while the problem of wear as a direct result of abrasion may be overcome, a new problem is created due to the tendency of these components to crack and fracture. Since the bell rod, small bell and sealing surfaces are all located in the feeding hopper of the blast furnace, they are subjected to the impact of tramp material, scrap metal or pig iron which is added from time to time to the blast furnace burden which is being loaded into the hopper and, consequently, any brittle materials which are located therein are likely to be cracked or chipped by these impact forces,

An example of a wear ring assembly for a blast furnace bell rod is illustrated in US. Pat. No. 3,144,145 dated Aug. 11, 1964, C. Steckle. If the Steckle segments were made from a brittle wear-resistant material they would be subject to the cracking and chipping previously referred to when the hopper is loaded with raw material. lf, on the other hand, the wear rings are made from a ductile material, they will have to have a very substantial thickness to have a worth while useful life. The impact forces applied by the material impinging against the side will be directed in a generally downwardly direction as the load is falling into the hopper with the result that chipping and cracking is more likely to occur adjacent to the lower annular suflace of the wear ring and as Steckle does not provide any means for inhibiting this cracking, the impact effect on a wear ring such as Steckles formed from a brittle wear-resistant material could be very substantial.

The small bell itself is also subjected to considerable abrasion and impact loading from the raw material used to feed the furnace. Again, numerous attempts have been made to provide a protective covering for the surface of the bells. However, none of the known structures have provided a readily replaceable abrasion and impact resisting surface for a small bell. In many blast furnaces which are presently in use, it is accepted that the bell surface will wear and the complete bell must be replaced from time to time during the life of the furnace. This costly and undesirable situation is accepted despite the fact that numerous attempts have been made to provide replaceable abrasion-resistant surface coverings. A typical example of the blast furnace bell with special wear plates is illustrated in US. Pat. No. 1,952,712, dated Mar. 27, 1934, issued to if. F. .luengling. The structure shown in this patent includes rolled plate material which is secured to the conically shaped surface of the bell. The wear resistance of rolled plate is not generally accepted as being particularly good and consequently the improvement provided by this structure is somewhat limited. A further disadvantage with the known type of reinforcing elements is that they are made in relatively large units such that if one element is damaged, a substantial portion of the material must be replaced and, furthermore, they are not readily removable from the frame of the bell. The attempts which have been made to provide improved wear-rcsistant characteristics to the surface of the bell have generally amounted to modifications to known bell structures and they have not introduced any dramatic change in the bell construction which would result in the forming of a bell which has improved wear characteristics.

The efificiency of operation of a blast furnace is also influenced by the efi'iciency of the seal which is formed between the sealing surface of the bell and the sealing surface of the hopper when the hopper is closed by the bell. This applies particularly to modern high tonnage blast furnaces designed for high top pressures. The sealing ring is subjected to the impact of this opening and closing forces which in the normal 4 to 5 year life of a sealing ring is likely to occur more than about a million times. If, as a result of any cracks or chips formed in the sealing surface of the bell, the hot gases are allowed to escape from the furnace, the efficiency of operation of the furnace may be reduced substantially. Furthermore, if a small chip or crack should appear in the sealing surface of the bell, the hot gases which are allowed to escape through these cracks may cause rapid enlargement of these cracks or chips by erosion, The hot gages are usually heavily laden with dust particles and, due to the pressure within the furnace, the abra sive nature of the dust laden atmosphere may very quickly enlarge any minor defect which occurs in the sealing surface of the bell. Again, numerous attempts have been made to provide readily replaceable sealing surfaces. One example of a replaceable sealing ring is defined in US. Pat. No. 3,275,310, dated Sept. 27, 1966, and issued to R. P. Hanne. The structure shown by llanne does not reduce the amount of wear which will occur in the area of the sealing surfaces but it does pro vide a means for replacing the worn sealing surface of the bell. If the replaceable sealing surface component is made from a brittle material, it may chip or crack when it is subjected to impact forces during the transfer of the load from the hopper into the furnace or from the closing action of the bell against the hopper. If a ductile material is used in the construction of the replaceable sealing ring member, it will wear very rapidly when subjected to the abrasion of the load transferring from the hopper into the furnace.

SUMMARY The present invention provides an improved wear ring seg ment for forming a protective sleeve around the bell rod of a blade furnace bell. The improved segments are formed from a laminate consisting of a brittle abrasive-resistant component and a ductile impact-resistant component. The two components are bonded to one another so as to present a wear resisting surface formed from alternately disposed layers of the first and second components such that the wear surface will have the combined characteristics of the components. Preferably, the ductile component will be located at the lower edge of the wear surface.

The present invention also provides an improved wear ring segment for a bell of a blast furnace. The segment is formed from an arcuateshaped laminate which has an outer wear surface which is obliquely disposed and. has a greatest radius of curvature at the lower edge thereof. The laminate is formed from two components. The upper component is a wearresistant brittle alloy of substantial thickness and the lower cornponent is a ductile material having a thickness which is substantially less than the thickness of the upper component. A plurality of wear ring segments are adapted to be mounted onto a bell frame so as to present a wear surface which consists of alternately disposed portions of said first and said second components.

A still further embodiment of this invention provides removable sealing ring assembly for a blast furnace bell. The removable assembly includes at least two ring elements adapted to extend around the periphery of the lower end of the bell to form a continuous sealing ring. Each of the ring elements are formed from a plurality of alternately disposed layers of a first and a second component. The first component consists of a wear-resistant brittle alloy of substantial thickness and the second component consists of a ductile material having a thickness less than the thickness of the first component. The outer surface of the rings which form the sealing surfaces are formed from alternately disposed sections of the first and second component to thereby provide a sealing surface which provides both abrasive wear-resistant characteristics and impact-resistant characteristics.

PREFERRED EMBODIMENT The invention will be more clearly understood after reference to the following specification read in conjunction with the drawings, wherein FIG. 1 of the drawings diagrammatically illustrates the hopper portion of a blast furnace including a small bell assembly;

FIG. 2 is a pictorial illustration of a stack of wear rings for protecting the support shaft of a small bell or the like,

FIG. 2a is a pictorial view of a segment of a wear ring;

FIG. 3 is a partially sectioned view of a small bell according to an embodiment of the present invention; and

FIG. 4 is an enlarged detail view of a portion of a small bell according to the present invention.

With reference to FIG. 1 of the drawings, the reference numeral It) refers generally to a typical blast furnace, small bell construction including a hopper 12, a sealing surface 14 at the lower end thereof for sealing the engaging small bell 16 when the small bell is in the elevated position. The small bell 16 is carried by a support shaft or bell rod 18 and the large bell rod 20 extends downwardly from the small bell. The present invention provides wear-resisting segments for protecting the support bell rod is, the conically shaped surface of the small bell l6 and the sealing surface of the small bell 16. The wear ring assembly for protecting the support shaft 18 is shown in detail in FIG. 2 of the drawings. The wear ring assembly consists of a plurality of layers of wear rings mounted one on top of the other and each consisting of a semicircular segment 22. Each of the segments 22 are formed from a laminate consisting of a first relatively thick component 24 and a second relatively thin component 26. The thick component 24 is preferably made from a wear-resistant brittle alloy while the thin component 26 is preferably made from a ductile material. The brittle material 24 is preferably formed of a cast alloy of a martensiticstinitic matrix containing finely dispersed carbides compatible with the matrix material, the carbides being selected from the group consisting of the carbides of iron, chromium, molybdenum tungsten vanadium and titanium. The second ductile component 26 is preferably made from a machinable and weldable ferrous material. The ratio of the thickness of the brittle material to the thickness of the ductile material is preferably in the range of three to one to to one. The brittle material 2 is cast with three U-shaped recesses 28 extending inwardly from the inner circumferential edge thereof. The recesses 28 are spaced from the ends of each semicircular segment a distance approximately equal to half the distance between the next adjacent recess. By arranging the recesses 28 in this manner, they are all evenly spaced from one another and two segments are placed together to form a continuous ring. Three locking pins 3%) are welded to the ductile component 26 to extend downwardly therefrom in axial alignment with the recesses 28 formed in the same segment. To form a sleeve for protecting the support shaft 18, a plurality of segments are arranged in a stacked relationship as shown in FIG. 2 surrounding the support shaft. By spacing the recesses and locking pins in the circumferentially spaced relationship previously described, it is possible to arrange the abutting end faces of each wear ring at a different circumferential position as shown in FIG. 2. By arranging the rings in a staggered relationship the seams do not form continuous openings in which fine material may become lodged and concentrated on opposite sides of the bell rod. The support sleeve which is formed by the wear rings illustrated in FIG. 2 is characterized by the alternately arranged layers of brittle abrasion resistant material and ductile impact-resistant material.

FIGS. 3 and 4 of the drawing illustrate the structure of the small bell assembly. The assembly includes a substructure or frame generally indicated by the reference numeral 32. The frame is generally conically shaped and consists of two sections bolted together along oppositely disposed flanges 34. Each of the sections is formed with a shoulder 36 which is adapted to fit into the conventional mounting ring of the bell rod lb. A plurality of circumferentially extending recesses, each having a vertical wall section 38 and a horizontal wall section 44 are formed on the surface of the frame 32. This stepped structure provides a plurality of shoulders of increasing diameter. Towards the lower end of the small bell, the frame is formed with an enlarged vertical wall 42 which ex tends downwardly to adjacent the bottom of the frame to meet an enlarged horizontal wall 44. This enlarged vertical wall is formed in the area of the small bell which forms the sealing surface. A recess 46 is formed in the housing adjacent the joint faces of the pair of frame members to provide clearance for the sealing ring mounting means.

Each of the circumferentially extending recesses of the frame is adapted to support a wearresistant ring. Each of the wear-resistant rings are formed from a plurality of arcuateshaped segments 50 (see FIG. 4). The segments are again formed from a composite laminate consisting of a first brittle component 24 and a second ductile component 26. The front face 52 which forms the wear surface of each segment is obliquely inclined such that the wear surface is disposed of an upper portion of brittle resistant material and a lower portion of ductile material. This combination is important as it will provide a surface which will resist both abrasion and impact forces. If the segment was made from a single piece of brittle wear-resistant material it would tend to chip and crack along the lower edge under the influence of impact forces. Any crack which developed in the surface 54 might extend downwardly through the body of the brittle material until it reaches the ductile material, at which point it would stop. The ductile material will tend to hold the brittle material together, thereby preventing wholesale cracking and chipping of the brittle material in the area of the lower edge where it has a minimum cross section. It is, therefore, an important feature of the present invention to provide a wear surface which consists of a large area of abrasion-resistant material and a small area of ductile impact absorbing material. The ductile materia1 is disposed below the brittle abrasion-resistant material so that any cracking in the brittle material will terminate at the ductile material.

Each of the segments also has a plurality of mounting pins 30 which are adapted to fit in a free fitting sliding relationship within the recesses 280 which are formed in the subfrarne 32 at uniformly circumferentially spaced intervals. The pins 30 are again mounted so that two segments may be placed side by side in a close fitting end-to-end relationship at any point around the circumference of the frame. When the wear segments become excessively worn, they may be removed and replaced with the result that the subframe 32 may be reused. Each of the segments are held in position on the frame by the locking pins previously described and by the fact that they are mounted one on top of the other in a stacked relationship. In effect, this part of the protective surface of the bell is a continuation of the system of half rings previously described for the protection of the bell rod.

A replaceable sealing ring 66 is mounted adjacent the lower end of the frame. Sealing ring 61 consists of a pair of semicircular rings 62 of L-shapecl cross section adapted to fit within the enlarged recess formed at the lower end of the frame. The half rings or brackets 62 have lugs 64 secured adjacent their end faces and the lugs 64 are bolted together to form a full circle. One pair of lugs dd is located at the upper inner edge of the rings to project into the recess as and the other lugs ll ii project downw' rdly from the bottom face. The half ring is secured to the frame flange by screws tilt which are arranged at unifomily spaced intervals about the circumference of the ring and tack welded in position. 'llhe wear surface is provided by a pair of laminated inserts t ll, one of which is carried by each ilf ring n2. Each of the wear rings 7th is semicircular and the ends are adapted to abut one another in a closeiitting relationship when the half rings bit are clamped together. Each of the rings 7& consists of alternately disposed layers of the first brittle component 2d and the second ductile component in the embodiment illustrated, there are five layers of ductile component and four layers of brittle component. various layers are bonded together rather than loosely staclted upon one another in order to present a continuous sealing surface for engagement with the sealing surface lidof the hopper Due to the importance ofmaintaining a good seal, the sealing ring is made in a plurality of layers rather than a single combination laminate such as the laminates used in the rings which form the wear surface of the bell. The upper ductile layer of each ring '7lll is welded to the upper edge of the half ring support. oil as shown by the weld '72. Similarly, the lowest ductile layer is welded to the half ring by weld 7d. The half ring supports are secured to the frame by conventional bolts which are tacit welded onto the frame to extend downwardly therefrom to pass through the horizontal flange dd to receive a not on their lower ends. A further laminate dd is preferably mounted at the outer peripheral edge of each half ring with the lower ductile component thereof welded to the underside of the half ring 62. The laminate serves to protect the outer edge of the half ring From the foregoing description of the preferred embodiments, it will be apparent that the present invention provides an improved bell construction for a blast furnace which is capable of withstanding the substantial abrasive and impact forces encountered within a blast furnace hopper.

included in the impact forces is the force applied to the bell to close the sealing surface against the seat 1d. During the operational life of a furnace between relining operations the bell is likely to open and close about 1,000,080 times and consequently the impact forces and crushing forces applied between the bell sealing surface and the seat are a very significant factor in the life of the furnace. The present invention provides a readily removable sealing ring which is capable of wearing much longer than those presently available.

The ductile element of the laminate serves to arrest any cracks which may develop in the brittle material and the brittle element serves to increase the resistance to abrasion.

What l claim as my invention is:

ll. A wear ring segment for a bell of a blast furnace or the like comprising an arcuate-shaped laminate having upper, lower, inner and outer surfaces, said outer surface forming the wear surface of the segment, said laminate consisting of an upper component of a wear-resistant brittle alloy of substantial thickness, and a lower component of a ductile material having a thickness which is substantially less than the thickness of the upper component, said upper and lower components being bonded to one another, said outer surface being inclined from the lower edge thereof to the upper edge in a direction towards said inner surface such that the obliquely disposed outer wear surface consists of an upper portion of wear resistant brittle alloy of substantial surface area and a lower portion of ductile metal having a surface area which is substantially less than the surface area of the wear-resistant material, said outer and inner surfaces of said ring being arcuately shaped to conform to the curvature of the blast furnace bell, said lower component being provided with mounting means adapted to secure said segments to a bell frame.

It. A wear ring segment as claimed in claim ll wherein said n'iounting means consists of a plurality of pins secured to the lower surface of said lower component by welding; and extenddistance substantially equal to halt the distarrc lieu jacent pins such it the order of a of no mpmcnts may abut in a close filtering relationship wl'icn mounted on a bell frame.

El. 1t wear rin segment for a bell of a blast fur lilre comprising; an arcuate-shaped lamir lower, inner and outer surfaces, the outer su wear-resistant sur" ce, said laminate con u; of a plurality of alternately disposed components, a .irst or .a id components consisting of a wear-resistant brit alloy of substantial thickness, the second component consisting of u ductile material having a thickness which is substantially less than the thickness of the brittle component, said. first and second components being arranged one on top of the other in a plurality of layers and bonded to one another to form a composite laminate, the bottom layer of the composite laminate being one of said second components, the outer inn-er faces of the laminate being formed with a longitudinal arcuate curvature, the outer surface of the laminate being inclined from the lower edge thereof to the upper in a direction towards said inner surface such that the lower surface of the laminate has a greater width than the upper surface of the laminate, the obliquely disposed outer surface being. formed from alternately arranged portions of said first corrnent and said second component, the lowermost portion or the outer surface being formed from said second component to prevent chipping of portions of the brittle component at the lower edge of the segment.

t. A bell assembly for a blast furnace or the like wherein the flow of raw material into the furnace regulated by the reciprocating movement of a main bell rod which is located centrally of the input passage and which erves to move the sealing surface of the bell into and out of ealing engagement with the sealing surface of the wall of the input cl'iarnber, said bell comprising: a support frame which has a generally frustoconical shape, said frame being formed from at least two sections which are releasably sccurablc to one another along a sub ntially vertical plane, mounting means for mounting said frame onto said shaft for movement therewith in use, a plurality of circumferentially extending recesses each formed in the outer conical surface of said frame, the diameter of successive circumfercntially extending recesses being greater than the preceding recess from the upper end of said frame to the lower end of the frame, a wear ling assembly relcasably mounted in each of said recesses, each successive wear ring assembly being of increased diameter f cm the uppermost as sembly to the lowermost assembly, said wear ring assemblies cooperating with one another to form contrmlous wcar-rcsistant outer surface on the frame, each of said wear ring asscrnblies being formed from at least two arc-uatc's," ed segments, the sealing surface of the bell being formed by the outer surface of a wear ring assembly.

A bell assembly as claimed in claim d wherein each of said wear ring segments comprises an arcuateshaped laminate having upper, lower, inner and outer surfaces, said outer surface forming the wear surface of the segment, said laminate consisting of an upper component of a wearu'esistant brittle alloy of substantial thickness, and a lower component of a ductile material having a thickness which. is substantially less than the thickness of the upper component, said upper and lower components being bonded to one another, rid outer surface being inclined from the lower edge thereof to the upper edge in a direction towards said inner surface such that the obliquely disposed outer wear surface consists of an upper portion of wear-resistant brittle alloy of substantial surface area and a lower portion of ductile metal having a surface area which is substantially less than the surface area of the wear-resistant material, said outer and inner surfaces of said ring being arcuately shaped to conform to the curvature of the hit: or the having upper, cc forming the blast furnace bell, said lower component being provided with mounting means adapted to secure said segments to a bell frame.

6. A wear ring segment as claimed in claim wherein said mounting means consist of a plurality of pins secured to the lower surface of said component by welding and extending vertically downwardly therefrom to engage complementary openings formed in said frame.

7. In a blast furnace assembly of the type having a removable sealing ring assembly adapted to sealingly engage a conical-shaped sealing surface at the lower end of a blast furnace hopper to control the flow of raw material into the furnace, the improvement wherein said sealing ring assembly comprises,

a. at least two ring elements adapted to extend around the periphery of the lower end of the bell to form a continuous sealing ring,

b. mounting means for mounting said elements on said bell,

c. each of said ring elements consisting of a laminate having upper, lower, inner and outer surfaces,

d. said outer surface forming the sealing surface of said bell upon assembly,

e. each of said laminated rings being formed from a plurality of alternately disposed layers of a first component which consists of a wear-resistant brittle alloy of substantial thickness and a second component which consists of a ductile material having a thickness which is substantially less than the thickness of the first component,

. the lowermost layer of the laminate being formed from said second component,

g. said outer surface of each ring being inclined from the lower edge thereof to the upper edge in a direction towards the inner surface such that the obliquely disposed outer sealing surface consists of alternately disposed sections of said first and second components.

8. A blast furnace bell assembly as claimed in claim 7 wherein the upper and lowermost layers of said laminate are formed from said first component.

9. In a blast furnace as claimed in claim 7 the further improvement wherein said mounting means comprises a removable support bracket adapted to be mounted adjacent to the lower edge of the bell frame, the support bracket having an L- shaped annular recess adapted to receive and support said ring elements and means for securing said support bracket to said frame.

10. The improvement of claim 9 wherein said support bracket is formed in at least two sections which are secured to one another to form a complete ring.

11. The improvement of claim 9 wherein the bell of the furnace is formed with a horizontally extending annular ledge at the lower end thereof to support said support bracket.

12. The improvement of claim 9 wherein the uppermost layer of said laminate is formed from said first component and it is secured to said support bracket by welding.

H3. The improvement of claim 11 wherein said support brackets are formed with lug means for securing mjacent sections thereof, said lug means including first lug means at the upper edge of each end of a bracket extending radially inwardly therefrom, said bell being formed with a vertically extending wall portion inwardly from said horizontal ledge to form an L-shaped recess therewith, at least two radially inwardly extending depressions formed in said vertical wall to provide clearance for said radially inwardly projecting legs of said support brackets.

14. A wear ring segment for protecting the bell rod of a blast furnace bell or the like comprising, an arcuate-shaped body having an inner arcuate-shaped surface having a curvature adapted to fit freely around the curvature of the bell support shaft, said body also having an outer arcuate-shaped surface and a pair of opposed transverse surfaces extending between said inner and outer arcuate surfaces, and a pair of end surfaces, said body being formed from a laminate consisting of two components, the first of said components forming a first of said transverse surfaces and consisting of a wear-resistant brittle alloy of substantial thickness, and a second component forming the second of said transverse surfaces and consisting of a ductile material having a thickness which is substantially less than the thickness of the first component, a plurality of locking pins means secured to said second component and extending outwardly from said second transverse surface, a plurality of recesses formed in said first component in axial alignment with the locking pins formed in said first component, said recesses being adapted to slidably receive a locking pin of the same proportions as the said locking pins carried by said second components whereby a plurality of segments may be stacked one on top of the other and held in position by the cooperation of the locking pins of one segment with the locking pin recesses of an adjacent segment.

15. A wear ring segment as claimed in claim 14 wherein said arcuate-shaped body extends through such that two such segments may cooperate with one another to form a complete ring.

16. A wear ring segment as claimed in claim 14 wherein said locking pins are circumferentially spaced from one another a distance equal to twice the circumferential distance between the end walls of the segment and the closest locking pins whereby upon assembly of the segments of the wear ring the locking pins are located at substantially uniformly spaced intervals to permit the end faces of each successive ring to be arranged out of alignment with one another to prevent the formation of a single continuous joint extending longitudinally of the bell rod.

17. A protective sleeve for a bell rod of a blast furnace formed from a plurality of wear rings arranged in a stacked relationship, one on top of the other, each wear ring consisting of at least two arcuate-shaped segments as claimed in claim M. 

1. A wear ring segment for a bell of a blast furnace or the like comprising an arcuate-shaped laminate having upper, lower, inner and outer surfaces, said outer surface forming the wear surface of the segment, said laminate consisting of an upper component of a wear-resistant brittle alloy of substantial thickness, and a lower component of a ductile material having a thickness which is substantially less than the thickness of the upper component, said upper and lower components being bonded to one another, said outer surface being inclined from the lower edge thereof to the upper edge in a direction towards said inner surface such that the obliquely disposed outer wear surface consists of an upper portion of wear-resistant brittle alloy of substantial surface area and a lower portion of ductile metal having a surface area which is substantially less than the surface area of the wearresistant material, said outer and inner surfaces of said ring being arcuately shaped to conform to the curvature of the blast furnace bell, said lower component being provided with mounting means adapted to secure said segments to a bell frame.
 2. A wear ring segment as claimed in claim 1 wherein said mounting means consists of a plurality of pins secured to the lower surface of said lower component by welding and extending vertically downwardly therefrom to engage complementary openings formed in the frame of the blast furnace bell, the mounting pins being uniformly spaced from one another and the outer pins being spaced from the end of the segment a distance substantially equal to half the distance between adjacent pins such that the order of a pair of adjacent segments may abut in a close filtering relationship when mounted on a bell frame.
 3. A wear ring segment for a bell of a blast furnace or the like comprising an arcuate-shaped laminate having upper, lower, inner and outer surfaces, the outer surface forming the wear-resistant surface, said laminate consisting of a plurality of alternately disposed components, a first of said components consisting of a wear-resistant brittle alloy of substantial thickness, the second component consisting of a ductile material having a thickness which is substantially less than the thickness of the brittle component, said first and second components being arranged one on top of the other in a plurality of layers and bonded to one another to form a composite laminate, the bottom layer of the composite laminate being one of said second components, the outer and inner faces of the laminate being formed with a longitudinal arcuate curvature, the outer surface of the laminate being inclined from the lower edge thereof to the upper edge in a direction towards said inner surface such that the lower surface of the laminate has a greater width than the upper surface of the laminate, the obliquely disposed outer surface being formed from alternately Arranged portions of said first component and said second component, the lowermost portion of the outer surface being formed from said second component to prevent chipping of portions of the brittle component at the lower edge of the segment.
 4. A bell assembly for a blast furnace or the like wherein the flow of raw material into the furnace is regulated by the reciprocating movement of a main bell rod which is located centrally of the input passage and which serves to move the sealing surface of the bell into and out of sealing engagement with the sealing surface of the wall of the input chamber, said bell comprising: a support frame which has a generally frustoconical shape, said frame being formed from at least two sections which are releasably securable to one another along a substantially vertical plane, mounting means for mounting said frame onto said shaft for movement therewith in use, a plurality of circumferentially extending recesses each formed in the outer conical surface of said frame, the diameter of successive circumferentially extending recesses being greater than the preceding recess from the upper end of said frame to the lower end of the frame, a wear ring assembly releasably mounted in each of said recesses, each successive wear ring assembly being of increased diameter from the uppermost assembly to the lowermost assembly, said wear ring assemblies cooperating with one another to form a continuous wear-resistant outer surface on the frame, each of said wear ring assemblies being formed from at least two arcuate-shaped segments, the sealing surface of the bell being formed by the outer surface of a wear ring assembly.
 5. A bell assembly as claimed in claim 4 wherein each of said wear ring segments comprises an arcuate-shaped laminate having upper, lower, inner and outer surfaces, said outer surface forming the wear surface of the segment, said laminate consisting of an upper component of a wear-resistant brittle alloy of substantial thickness, and a lower component of a ductile material having a thickness which is substantially less than the thickness of the upper component, said upper and lower components being bonded to one another, said outer surface being inclined from the lower edge thereof to the upper edge in a direction towards said inner surface such that the obliquely disposed outer wear surface consists of an upper portion of wear-resistant brittle alloy of substantial surface area and a lower portion of ductile metal having a surface area which is substantially less than the surface area of the wear-resistant material, said outer and inner surfaces of said ring being arcuately shaped to conform to the curvature of the blast furnace bell, said lower component being provided with mounting means adapted to secure said segments to a bell frame.
 6. A wear ring segment as claimed in claim 5 wherein said mounting means consist of a plurality of pins secured to the lower surface of said component by welding and extending vertically downwardly therefrom to engage complementary openings formed in said frame.
 7. In a blast furnace assembly of the type having a removable sealing ring assembly adapted to sealingly engage a conical-shaped sealing surface at the lower end of a blast furnace hopper to control the flow of raw material into the furnace, the improvement wherein said sealing ring assembly comprises, a. at least two ring elements adapted to extend around the periphery of the lower end of the bell to form a continuous sealing ring, b. mounting means for mounting said elements on said bell, c. each of said ring elements consisting of a laminate having upper, lower, inner and outer surfaces, d. said outer surface forming the sealing surface of said bell upon assembly, e. each of said laminated rings being formed from a plurality of alternately disposed layers of a first component which consists of a wear-resistant brittle alloy of substantial thickness and a second component which consists of a ductile material having A thickness which is substantially less than the thickness of the first component, f. the lowermost layer of the laminate being formed from said second component, g. said outer surface of each ring being inclined from the lower edge thereof to the upper edge in a direction towards the inner surface such that the obliquely disposed outer sealing surface consists of alternately disposed sections of said first and second components.
 8. A blast furnace bell assembly as claimed in claim 7 wherein the upper and lowermost layers of said laminate are formed from said first component.
 9. In a blast furnace as claimed in claim 7 the further improvement wherein said mounting means comprises a removable support bracket adapted to be mounted adjacent to the lower edge of the bell frame, the support bracket having an L-shaped annular recess adapted to receive and support said ring elements and means for securing said support bracket to said frame.
 10. The improvement of claim 9 wherein said support bracket is formed in at least two sections which are secured to one another to form a complete ring.
 11. The improvement of claim 9 wherein the bell of the furnace is formed with a horizontally extending annular ledge at the lower end thereof to support said support bracket.
 12. The improvement of claim 9 wherein the uppermost layer of said laminate is formed from said first component and it is secured to said support bracket by welding.
 13. The improvement of claim 11 wherein said support brackets are formed with lug means for securing adjacent sections thereof, said lug means including first lug means at the upper edge of each end of a bracket extending radially inwardly therefrom, said bell being formed with a vertically extending wall portion inwardly from said horizontal ledge to form an L-shaped recess therewith, at least two radially inwardly extending depressions formed in said vertical wall to provide clearance for said radially inwardly projecting legs of said support brackets.
 14. A wear ring segment for protecting the bell rod of a blast furnace bell or the like comprising, an arcuate-shaped body having an inner arcuate-shaped surface having a curvature adapted to fit freely around the curvature of the bell support shaft, said body also having an outer arcuate-shaped surface and a pair of opposed transverse surfaces extending between said inner and outer arcuate surfaces, and a pair of end surfaces, said body being formed from a laminate consisting of two components, the first of said components forming a first of said transverse surfaces and consisting of a wear-resistant brittle alloy of substantial thickness, and a second component forming the second of said transverse surfaces and consisting of a ductile material having a thickness which is substantially less than the thickness of the first component, a plurality of locking pins means secured to said second component and extending outwardly from said second transverse surface, a plurality of recesses formed in said first component in axial alignment with the locking pins formed in said first component, said recesses being adapted to slidably receive a locking pin of the same proportions as the said locking pins carried by said second components whereby a plurality of segments may be stacked one on top of the other and held in position by the cooperation of the locking pins of one segment with the locking pin recesses of an adjacent segment.
 15. A wear ring segment as claimed in claim 14 wherein said arcuate-shaped body extends through 180* such that two such segments may cooperate with one another to form a complete ring.
 16. A wear ring segment as claimed in claim 14 wherein said locking pins are circumferentially spaced from one another a distance equal to twice the circumferential distance between the end walls of the segment and the closest locking pins whereby upon assembly of the segments of the wear ring the locking pins are located at substantially uniformly spaced intervals To permit the end faces of each successive ring to be arranged out of alignment with one another to prevent the formation of a single continuous joint extending longitudinally of the bell rod.
 17. A protective sleeve for a bell rod of a blast furnace formed from a plurality of wear rings arranged in a stacked relationship, one on top of the other, each wear ring consisting of at least two arcuate-shaped segments as claimed in claim
 14. 